Teaching Organic Farming and Gardening

Soil Biology and Ecology

Unit 2.3 | 3
Introduction

Unit Overview

This unit introduces students

to the biological properties and

ecosystem processes of agricultural

soils. Students will review the

constituents of soils and the physical

characteristics and soil ecosystem

processes that can be managed to

improve soil quality. Demonstrations

and exercises will introduce students

to techniques used to assess the

biological properties of soils. Such

assessments help inform decisions

about soil management with the goal

of maintaining crop productivity

and soil health in certified organic

farming and gardening systems.

Introduction: Soil Biology and Ecology

MOdes Of instrUctiOn

> LECTURE (1 LECTURE, 1.5 HOURS)

Class lecture outline covers the basic biology and ecosystem

processes of soils, focusing on ways to improve soil quality

for organic farming and gardening systems.

> DEMONSTRATION 1: ORgANIC MATTER DECOMPOSITION

(1.5 HOURS)

This exercise demonstrates how to assess the capacity of

different soils to decompose organic matter. Discussion

questions ask students to reflect on what environmental

and management factors might have influenced the test

results and what the results suggest about nutrient cycling

rates and the quality/health of the soils tested.

> DEMONSTRATION 2: SOIL RESPIRATION (1 HOUR)

The demonstration outline covers the use of Draeger gas

detection tubes for measuring carbon dioxide levels liber-

ated from soils as an indicator of soil biological activity

and soil quality/health.

> DEMONSTRATION 3: EARTHwORM POPULATION

(1 HOUR)

The demonstration covers the preparations, material used

to sample soil for the presence and abundance of earth-

worm types. Discussion questions ask students to consider

the presence and abundance of certain earthworm types as

indicators of soil quality/health.

> DEMONSTRATION 4: SOIL ARTHROPOD (1 HOUR)

The demonstration covers the preparation and materials

used to collect and identify soil arthropods. Discussion

questions ask students to consider the presence and diver-

sity of soil arthropods as indicators of soil quality/health.

> HANDS-ON ExERCISE: CARBON AND NITROgEN

MINERALIzATION (0.5 HOUR)

The demonstration covers the preparations and materi-

als used in estimating how much mineral N (nitrate and

ammonium) is liberated from organic matter inputs. This

exercise simplifies the complex processes of the soil food

web that occur during decomposition, as organic matter is

converted into nutrient forms that plants can use.

> ASSESSMENT QUESTIONS (1 HOUR)

Assessment questions reinforce key unit concepts and skills.